Model to Data Analysis of the Nuclear Equation of State at Extreme Temperature and Density

Scott Moreland, Duke University

Photo of Scott Moreland

At sufficiently high temperatures and densities quantum chromodynamics (QCD), the theory of the strong nuclear force, predicts a phase transition from bound states of protons and neutrons to a deconfined "soup" of subatomic quarks and gluons known as a quark-gluon plasma (QGP). Quite remarkably, the equation of state of this exotic phase of matter is rigorously calculable from the QCD Lagrangian using a numerical methodology known as lattice QCD. These calculations, while faithful in their representation of QCD, are limited by the precision of their numerics and hence return a best-fit prediction for the QGP equation of state as well as associated errors.

In this study we examine the effect of these errors, as well as systematic errors in the discrepancy of calculations conducted by different collaborations, on the hydrodynamic evolution of QGP fireballs produced in ultra-relativistic nuclear collisions. Our results indicate that discrepancies arising from the numerical limitations of modern lattice calculations are small and that state-of-the-art calculations of the QGP equation of state by the HotQCD and Budapest-Wuppertal collaborations predict hydrodynamic evolutions of the QGP fireball which are, for all practical purposes, indistinguishable. However, we find that previous parameterizations of the HotQCD equation of state that were calculated on courser lattices deviate measurably from either of these analyses, and hence should be avoided in future simulations.

Abstract Author(s): J.S. Moreland, R. Soltz